"Using satellite observations and models to understand processes in the chemistry-
climate system" 
 
"Tropospheric ozone (O3) and carbon monoxide (CO) are well known pollutants, 
also majorly affecting the ability of the atmosphere to cleanse itself of pollution 
(oxidizing capacity) and exerting a direct (O3) and indirect (CO and O3) influence on 
climate. In addition to being driven by natural and anthropogenic emissions, 
their concentrations also depend on a wide range of chemical and physical 
processes. O3 is a secondary pollutant (not primarily emitted) and CO is one of its 
precursors, but the relationship between the abundances of the two species is not 
easily defined, as it also depends on the concentrations of other trace gases and on 
meteorological conditions. In this talk, results from a study that looks into the 
dependence of O3 concentrations on CO levels on large spatial scales and relatively 
short timescales will be shown. This study is based on a correlation analysis that 
involves multi-year data from the Tropospheric Emission Spectrometer (TES), 
which is the first satellite instrument that measures tropospheric O3 and CO profiles 
simultaneously. The O3-CO correlation maps produced are compared to results 
produced by two state-of-the-art chemistry-climate models, with which we also 
perform sensitivity experiments to understand the drivers of different correlation 
features. We suggest that this approach could be a useful addition to multi-model 
intercomparisons in order to investigate if models capture O3 and CO levels well 
and for the right reasons. This work will also be the basis of a series of planned 
studies which will use various satellite products (gases, aerosols, lightning, clouds 
etc) to evaluate different processes in models."